Carburetor



B. WALKER CARBURETOR Jan. 16, 1968 2 Sheets$he t 1 Filed May 17, 1966 f3 fi Illlll Jan. 16, 1968 WALKER 3,363,886

CARBURETOR Filed May 17, 1966 2 Sheets-Sheet 2- United States Patent 3,363,886 CARBURETOR Brooks Walker, 1280 Columbus Ave., San Francisco, Calif. 94133 Filed May 17, 1966, Ser. No. 550,862 7 Claims. (Cl. 261-41) ABSTRACT OF THE DISCLOSURE A carburetor for improving combustion of an internal combustion engine during closed throttle operation. An orifice is formed in the throttle valve for passing air when the throttle valve is closed. A conduit in the form of a venturi tube is located to receive all air passing through the valve orifice in the closed position of the valve. A passage for inserting rich fuel mixture is arranged to discharge the mixture into the throat of the venturi tube whereby the collision with the air from the orifice atomizes the fuel. The tube is oriented to discharge the atomized mixture in a zone removed from the wall of the carburetor.

The invention relates to carburetor arrangements, especially in internal combustion engines and in particular to carburetion in the idle or low speed phases.

In one carburetor arrangement which is widely used, provision is made for carburetion in the idle and low speed phases by admitting a rich mixture of fuel and air into a chamber below a butterfly throttle valve into which an additional quantity of air to idle is admitted by adjusting the butterfly valve slightly open. It is a characteristic of such arrangements that the atomizing potential' of the limited collision of the rich fuel mixture and the air is not maximized. It is now suggested, in the arrangement according to the invention, that the carburetion in the idle and low speed phase may be substantially improved by providing for a butterfly which is fully closed at idle and has a port through which all air admitted is directed at a passage located within the mixing chamber which has the properties of a venturi tube. The rich fuel mixture is then admitted into this passage, at an advantageous port thereof, to be exposed to all incoming air to idle under conditions which are peculiarly conducive to producing a greatly improved homegeneous mixture of air and fuel, thus furthering objectives depending upon such homogeneous mixture.

It is one object of the invention to provide an improved carburetor.

It is a further object of the invention to produce a carburetor particularly effective in the idle and low speed phases of operation.

It is a third object of the invention to produce a carburetor which allows a more accurate control of the mixing process of air and fuel in the idle and low speed phases.

It is a fourth object of the invention to provide a carburetor which will produce a more homogeneous mixture of fuel and air.

It is a fifth object of the invention to provide an internal combustion engine which will operate more economioally.

It is a sixth object of the invention to provide an internal combustion engine which will discharge a lesser quantity of unburned hydrocarbons or smog producing components.

It is a seventh object of the invention to provide means for the modification of existing internal combustion carburetors or engines as well as for the inexpensive production of improved new or modified carburetors.

It is an eighth object of the invention to provide means whereby the other objects can be accomplished.

The invention is hereafter explained in reference to a preferred embodiment and illustrated in the drawings in which:

FIG. 1 shows a vertical section through a part of a conventional carburetor and certain elements according to the invention associated therewith.

FIG. 2 shows a vertical section according to FIG. 1 associated with elements of another embodiment of the invention.

FIG. 3 shows a vertical section through a portion of a carburetor and elements of another embodiment of the invention associated therewith.

FIG. 3A shows a detail of the FIG. 3.

FIG. 3B shows another detail of the embodiment disclosed in FIG. 3.

FIG. 1 shows the lower section of a carburetor, generally indicated at 1, which terminates in a flange 2 whereby it is attached by means of screws (not shown) in the general circumferential location indicated at 3, to an intake manifold 4 of an internal combustion engine. A butterfly valve 5 is disposed within the carburetor, on a shaft 6 and fastened by screws 7. Means are provided whereby the butterfly valve 5 may be set to a first position, as shown, in which it shuts off substantially all air communication from an upper part 8a of an air passage 8 to a lower part 8b past its upper edge 5a and lower edge 5b. Further means are provided where by the butterfly valve 5 can be set from the first engine idle position described above, through an infinite number of intermediate positions to a wide open position indicated by 50. In conventional arrangements special inventive concept in means are provided whereby the butterfly valve 5 may be set for purposes of carburetion in the idling and low speed phases to one of the intermediate positions mentioned above in which a desired quantity of air to idle is allowed to pass the edges 5a and 5b of the butterfly valve 5 and any opening between the edges of the butterfly valve 5 and the wall of the main throat 8 and enter the lower chamber 8b which constitutes the, and shall hereafter be designated as, the idle mixing chamber 811. Rich fuel and air are admitted through a passage 9 (in a conventional manner, not shown), past a transfer slot 10 through which it aspires some air from the chamber 8a when in the idle position of the butterfly 5, and further past the point 11a of a needle valve 11 with conventional spring 11b in a threaded bore to enter at last the idle mixing chamber 8b through a port 12. It is thus obvious from the description and FIG. 1, upon considerations more fully explained in the inventors copending application Ser. No. 544,246, that the air admitted from the upper chamber 8a into the idle mixing chamber 8b takes the form of two crescent-shaped streams which collide in succession with the relatively massive jet of incoming rich fuel and air mixture. Only a part of the incoming air is brought into immediate and positively controllable collision with the incoming rich fuel mixture. The conventional arrangement provides for no more than the simultaneous admission of air and the rich fuel mixture into the idle mixing chamber 8b.

The arrangement according to the invention provides for a butterfly valve 5 which is kept closed during the idling and slow speed phases, so that substantially no air is allowed to pass its edges, including the edges 5a and 5b. Substantially all air to idle admitted into the mixing chamber 812 is passed through a specially provided port 13 in butterfly 5. It is obvious that the air passing the port 13- will enter the space of the mixing chamber 8b in a concentrated high speed stream, as

distinguished from the two crescent-shaped streams in the conventional arrangement. The stream of air passing through the port 13 is not allowed to expand freely but directed into a tubular passage 14 which has interior features conforming to the principle of the generally known venturi tube. The port 12 is extended by means of a tube 15 so that its new terminal 12a is located in the passage 14. While it is a matter of discretion on the part of the artisan at which particular point of the passage 14 the extension 12a of port 12 is located, particularly satisfactory results have been obtained by cating it centrally with respect to the restriction 14a which constitutes a characteristic feature of the venturi tube. Moreover, satisfactory results have been obtained with a tube which is cut at a bias at its terminal end and so oriented that its shortest longitudinal element is located downstream with respect to the air coming from the port 13. However, the'cut and orientation of the tube 15 is a matter of discretion, to be determined by the artisan according to conditions and particular objectives. It is thus a characteristic of the arrangement according to the invention that substantially all air passing the butterfly valve 5 is managed positively after its entry into the space of the idle mixing chamber 8b and subjected to a strict regimen before it is allowed to expand. One of the objects of such positive management, which itself is ancillary to the objects defined above, is the more advantageous exposure of the rich fuel mixture to the incoming air. Another objective of the positive management of the air after its entry into the mixing chamber 8b is the directional regimen imposed upon the mixture of air and fuel which is delivered to the intake manifold 4. However, this feature has been described and is claimed in the inventors copending application Ser. No. 544,246 mentioned above.

Aside from the improvement in the mixing process, as described above, the inventor is concerned with the practical application of the invention beyond the purely functional aspect of positioning the passage 14 and the tube 15 in the space of the mixing chamber 8b. While a number of other solutions may suggest themselves to the artisan, it is suggested that modern methods of manufacture might lend themselves in particular to an arrangement in which the passage 14 is formed in an element 16 of an interponent 17 which is disposed between the carburetor 1 and the intake manifold 2. The interstitial elements 20 and 20a are gaskets of conventional type. At least one modern method of manufacture, viz die casting, would allow that all features necessary for the practical application of the invention be readily imparted to a single mechanical part.

Thus the tube 15 could be pressed into a hole provided for that purpose, unless the artisan prefers to provide the extension 12a of the port 12 entirely by imparting a suitable configuration to the material.

While the entire assembly could be held in place by the screws in the location 3, it would be convenient to provide a bore 17b with counter bore 17a in the interponent 17 and a threaded bore 1a in the carburetor in a convenient number of circumferential locations so that the interponent 17 could be preassembled on the carburetor 1 together with the gasket 20 into a subassembly removable en bloc when the engine is serviced.

As a convenience in the assembly of the part into the carburetor scheme, especially into engines already in use, the element 16 might be made upon considerable tolerance with respect to the wall of the chamber 8b and a closure around the rich fuel mixture port 12 provided by means of an O ring 18 located in a groove 19. Such matters of convenience are entirely within the scope of the art.

FIG. 2 shows a further possibility of imparting to a mechanical part the features necessary for the practical application of the invention and to associate such part with the carburetor. The element 16 is formed as an integral part of a ring 21 which is disposed within a bore 21a cut into the Wall of the mixing chamber 8b. A key element 21b is provided on the ring 21 which engages a receptacle 210 in the bore 21a to secure the ring 21, and thus the element 16, in the proper radial position with respect to the port 12. Such arrangements are also Within the scope of knowledge which may be expected of the artisan.

FIG. 2 further shows a throttle valve 22 which has been already disclosed in its function in the copending application Ser. No. 544,246. A threaded bore 24 in the element 16 receives a threaded portion 22b whereby the valve 22 is set against the pressure of a spring 25, so that its point 22a obstructs the passage 14 in an adjustable manner. For ease in assembly and to take up manufacturing tolerances, it is suggested that a hole 23 be provided in the carburetor 1, generally on the axis of the bore 24 but of conveniently larger'diameter. A rubber collar 27, shown without cross-hatching for the sake of clarity, of an inside diameter tightly embracing the stem of the valve 22 and of sufficient outside diameter to cover the hole 23 in any event, even if the valve 22 should be off center in the hole 23, would then provide a seal to prevent the admission of spurious air through hole 23. A washer 26, interposed between the spring 25 and the collar 27, would evenly distribute the deformation of the collar 27, causing it to close tightly around the stem of the valve 22 while at the same time sealing also the hole 23. It is obvious that the artisan, in choosing the dimensions of the rubber collar 27 and the washer 26, may by means of the closure suggested above provide a seal which Will be operative even if the valve 22 should not occupy the center of the hole 23. If the rubber collar 27 is made thick enough and the spring 25 correspondingly strong, the seal would accommodate even great pressure differentials.

FIGS. 3, 3A and 3B show another embodiment of the inventive concept in association with certain elements of a conventional carburetor. Parts designated by reference numerals shown in FIG. 1 are identical with those shown in and described for FIG. 1.

A hole 28 is cut into the butterfly valve 5 and receives a tubular element 29 which may be easily exchanged, as it is held by a snap ring 34 which engages a groove 34a and embraces the area of the butterfly valve 5 which immediately adjoins the hole 28 in conjunction with a shoulder 34b. A passage 29a in the tubular element 29 has a configuration which conforms to the principle of the venturi tube. It is obvious that the passage 29a is analogous to the passage 14 in FIG. 1. The rich fuel mixture is transported from the port 12 through a tube 32 inserted therein, then through a flexible tube 30 installed on the tube 32, to a discharge tube 2% similar to tube 15 in FIG. 1 which is inserted into the flexible tube 30. Although the tube 29b is shown on the engine side of the restriction in the venturi, it may be advantageous to put it at the intake side of the greatest restriction in said venturi in the butterfly as mentioned above. A wire coil 31 is wound around the flexible tube to impart resiliency to it and prevent kinking and sharp bends in the tube. The wire coil also assists in forming a convenient coiling, as shown in FIGS. 3 and 3A. The arrangement in FIG. 3, as described so far, is intended to function in the same manner as the arrangements of FIGS. 1 and 2. Its principal advantage is the ready exchangeability of the tubular element 29 which affords a measure of adjustment or adaptability by installing a tubular element intended for one operating condition instead of another which is more suitable for a different operating condition. While it is possible, and might be desirable, to allow air present in the upper chamber 8a to enter the passage 29a, the inventor has obtained particularly satisfactory results by excluding the air in the chamber 8b. Based upon the theory that the control of the mixing ratio of air and fuel is one of the keys to the control of objectionable waste products in the engine exhaust, it is suggested that the air which is to be admitted to the mixing chamber 3!) may advantageously be taken from a part of the carburetor located above the structure, indicated at So, which contains the main fuel nozzle (not shown) and preferably below the choke butterfly valve 37 in order to retain the advantage of the choking phenomenon Well known in the art and therefore not detailed here. A troublesome source of contamination is thus excluded. A duct 33 is provided for this purpose which has an intake terminal 33a and is led outside the carburetor body, bypassing the main venturi 30 as Well as the main fuel nozzle (not shown) in the structure St], to reenter through a hole 15 in the carburetor wall and make contact with the tubular structure 29 by means of a closely fitted discharge terminal 33b.

It is further contemplated and suggested that this arrangement, specifically the duct 33, might be modified by providing a valve 35 of conventional nature, having a spring 35a and a point 351) which function in the manner of the needle valve 11, to regulate the volume of air which is admitted through the duct 33, thus providing an adjustment of the engine idle speed.

As a further modification of the scheme shown in FIG. 3, and upon the results of experiments, it is suggested that carburetion may be significantly improved by controlling the aspiration of air into the fuel being delivered to the port 12. As mentioned earlier, some air is drawn into the fuel through the slot 10. The quantity of air so added to the fuel before it is subjected to the further mixing with the air passing through the butterfly valve 5 affects the mixing process. As shown in FIG. 3b, a choke wire 36 is attached to the butterfly valve 5 in such a manner that it will enter the transfer slot 10, and restrict the volume of air passing through it only when the butterfly valve 5 is closed in the idling or low speed phases of operation. As soon as the butterfly valve 5 is opened and the transfer slot begins to function as a transfer port (in a manner and for reasons well understood in the art and here not elaborated), the wire 36 is moved up to clear the slot below the partially opened butterfly valve 5 and its choking effect upon the air supplied to the fuel in the passage 9 cancelled. As a practical solution of the problem posed by the necessity of mounting the wire 36 on the butterfly valve 5, it is proposed that a notch 5d might be cut into the butterfly valve 5 and the wire 36, having a contoured end 36a which lies in a plane perpendicular to the plane of the part which enters the transfer slot 10, pinched in slot 5d by means of a deformation 5e. However, many methods are known to the art whereby a part of the nature of wire 36 may be attached to the butterfly valve 5.

The disclosure above and the drawings illustrate the invention in various forms and in its application to certain embodiments chosen by the inventor as a matter of mere convenience. To those skilled in the art many variations and other applications to widely differing embodiments will suggest themselves entirely within the concept of the invention and without departure from its spirit and scope. All such applications and potential uses are intended to be claimed belowdescription and drawings being intended as mere illustrations which do not indicate a limitation of the invention to devices of the kind shown, nor to the art of carburetors generally.

I claim as my invention:

1. A carburetor comprising a tubular body member, a valve pivotally mounted in said member for movement between and open position to allow maximum fluid flow therethrough and a closed position preventing fluid flow therethroug-h, means for admitting a stream of a rich fuel mixture through the wall of the member downstream of the valve in its closed position, a single opening through the valve for passage of a stream of fluid theret-hrough, a venturi conduit secured to the member and having one end thereof in sealing contact with the valve, in its closed position, around the opening, the other end of the conduit opening adjacent the center area of the member, and a passage between the ends connecting the admitting means to the conduit between the ends thereof.

2. A carburetor as defined in claim 1 wherein the passage exhausts in the neck of the conduit.

3. A carburetor as defined in claim 2 wherein the means for securing the conduit to the member comprises a ring recessed into the wall of the member, the venturi conduit comprising an extension integral with the ring, and means sealing the admitting means and passage against escape of fluid between the wall and extension.

4. A carburetor as defined in claim 3 further including means in the conduit for obstructing the flow of fluid therethrough.

5. A carburetor comprising a tubular body member, a valve pivotally mounted in said member for movement between an open position to allow maximum fluid flow therethrough and a closed position preventing fluid flow therethrough, an opening through the valve, a venturi conduit secured in said opening, means admitting fluid to the conduit end at the upstream side of the valve and means for conducting a rich fuel mixture: into the conduit.

6. A carburetor as defined in claim 5 wherein the conducting means comprises a flexible tube connected to the venturi conduit and to a rich fuel inlet in the wall of the member.

7. A carburetor as defined in claim 6 further including a wire coil wound around the flexible tube to prevent kinking and sharp bending.

References Cited UNITED STATES PATENTS 1,536,042 4/1925 Bessom 26141 1,665,239 4/1928 Wallace 26141 X 1,691,201 11/1928 Larkin 261-41 1,730,191 10/1929 Claudel 26141 1,902,603 3/1933 Wilson 261-41 1,935,350 11/1933 Chandler 26141 2,017,919 10/1935 Robbins 261-62 X 2,036,575 4/ 1936 Granville 26172 2,063,433 12/1936 Grenat 26156 X 3,151,604 10/1964 Walker et al. 26141 3,201,097 8/1965 Arndt 261-41 3,281,128 10/1966 Phillips.

FOREIGN PATENTS 493,329 4/1919 France.

HARRY B. THORNTON, Primary Examiner. TIM R. MILES, Assistant Examiner. 

